An organic light emitting device is a device which includes a thin film which contains a fluorescent organic compound or a phosphorescent organic compound and is interposed between an anode and a cathode.
Further, a hole and an electron are injected from the respective electrodes, whereby an exciton of the fluorescent compound or the phosphorescent compound is generated. Light is radiated upon return of the exciton to its ground state.
The recent progress of an organic light emitting device is significant, and the device suggests its potential to find use in a wide variety of applications because of the following reasons. The device shows a high luminance at a low applied voltage. In addition, the device has a variety of light emission wavelengths. Furthermore, the device can be a thin, light-weight light emitting device with high-speed responsiveness.
However, at present, an optical output with additionally high luminance, or additionally high conversion efficiency has been needed. In addition, the organic light emitting device still has many problems in terms of durability. For example, the device changes over time owing to long-term use, and deteriorates owing to an atmospheric gas containing oxygen, humidity, or the like.
Further, in the case where it is assumed that the device is applied to, for example, a full-color display, the device must emit blue light, green light, and red light each having good color purity. However, problems concerning the color purity of each of the blue light, the green light, and the red light have not been sufficiently solved yet.
In addition, examples of a material and an organic light emitting device each using a fluorene compound are disclosed in Japanese Patent Application Laid-Open Nos. H11-144875, H11-224779, H11-288783 and 2001-39933. However, each of the devices described in those documents has low external quantum efficiency and an insufficient duration lifetime.
In addition, examples of a material and an organic light emitting device each using an aromatic tertiary amine derivative are disclosed Japanese Patent Application Laid-Open Nos. H04-220995, 2002-324678, H05-234681 and H05-009471.